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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - Missing warning -Wthread-safety-negative when using capabilities in namespace scope"
href="https://bugs.llvm.org/show_bug.cgi?id=46354">46354</a>
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<th>Summary</th>
<td>Missing warning -Wthread-safety-negative when using capabilities in namespace scope
</td>
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<th>Product</th>
<td>clang
</td>
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<th>Version</th>
<td>trunk
</td>
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<th>Hardware</th>
<td>All
</td>
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<th>OS</th>
<td>All
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<th>Status</th>
<td>NEW
</td>
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<th>Severity</th>
<td>normal
</td>
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<th>Priority</th>
<td>P
</td>
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<th>Component</th>
<td>Frontend
</td>
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<th>Assignee</th>
<td>unassignedclangbugs@nondot.org
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<th>Reporter</th>
<td>aaronpuchert@alice-dsl.net
</td>
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<th>CC</th>
<td>llvm-bugs@lists.llvm.org, neeilans@live.com, richard-llvm@metafoo.co.uk
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<p>
<div>
<pre>With mutex.h from <a href="https://clang.llvm.org/docs/ThreadSafetyAnalysis.html#mutex-h">https://clang.llvm.org/docs/ThreadSafetyAnalysis.html#mutex-h</a>
and -Wthread-safety-negative, there is a warning on
class Foo {
Mutex mu;
public:
void foo() {
mu.Lock(); // acquiring mutex 'mu' requires negative capability '!mu'
mu.Unlock();
}
};
but not on
Mutex mu;
void foo() {
mu.Lock();
mu.Unlock();
}
That's inconsistent, and probably also unintended: "The analyzer assumes that
it holds a negative capability for any object that is not defined within the
current lexical scope. The scope of a class member is assumed to be its
enclosing class, while the scope of a global variable is the translation unit
in which it is defined." [1]
[1]
<a href="https://static.googleusercontent.com/media/research.google.com/en/us/pubs/archive/42958.pdf">https://static.googleusercontent.com/media/research.google.com/en/us/pubs/archive/42958.pdf</a></pre>
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